Seismic Performance Analysis Of Fifth-Class Timber Frame Under Typical Damage Types

The timber structure of Chinese ancient buildings carries the civilization history of the Chinese nation for thousands of years.It embodies the shining wisdom of ancient craftsmen,and reflects the humanistic characteristics of different times.Many existing timber structure buildings have survived hundreds or even thousands of years,and they still retain their original style,showing excellent seismic performance.However,many buildings have been exposed to the natural environment for a long time,suffering from the baptism of wind and frost and the destruction of earthquakes,which have caused varying degrees of damage to these buildings.Therefore,based on the guidance of typical damage,it is of great significance to study the seismic performance of timber frame with column foot damage and foundation settlement.In this paper,according to the provisions on the size of each component in the construction method,Through ABAQUS finite element software,the timber frame of fifth grades of wood integrity,column base damage and foundation settlement is established.The pseudo static and dynamic simulation analysis are carried out on these models.The effects of column base damage and foundation settlement on the deformation,hysteretic characteristics,energy consumption,acceleration and displacement of timber frame are studied.The main research results are as follows:(1)The hysteretic curves of each timber frame model are basically in the shape of "S",and the envelope area is small,The energy dissipation capacity of the timber frame is weak and the deformation capacity is strong.With the increase of horizontal loading displacement,the overall lateral deformation of each timber frame increases.The stress level of mortise joint and column foot joint increases,the lateral stiffness decreases,and the total input energy and hysteretic energy consumption increase.The increase of vertical counterweight increases the peak and extreme loads,lateral stiffness,total input energy and hysteretic energy dissipation of each timber frame,and the vertical counterweight plays an important role in the overall stability of the timber structure.(2)The damage of column base reduces the fullness of hysteretic curve and weakens the energy consumption capacity.The damage of column base reduces the yield,peak and extreme load of timber frame by 6.53% ～ 27.41%,and the lateral stiffness decreased by8.52% ～ 26.82%,and the lateral stiffness decreased by 8.52% ～ 26.82%,and the total input energy decreases.There is little difference in hysteretic energy consumption,and the damage of column foot has little effect on hysteretic energy consumption of the timber frame.(3)The foundation settlement leads to the increase of the initial lateral displacement of the timber frame.Compared with the intact structure,the overall and key node deformation and stress level of the foundation settlement timber frame increase,and the node damage and damage are more significant.The peak and extreme loads at the settlement end of the timber frame decreased by 8.60% ～ 26.89%,and the lateral stiffness decreased by 30.98% ～57.16%.The total input energy at the settlement end and non-settlement end of the timber frame decreases,and the hysteretic energy consumption increases.(4)The dynamic simulation analysis of each timber frame shows that the timber structure is more sensitive to low-frequency and long-period simple harmonic waves.The mortise and tenon joint is the key to energy dissipation and damping of the timber frame.The seismic isolation and damping effect of mortise and tenon joint is obvious when the input frequency and strength are large.The inter-story displacement angle of the timber frame decreases with the increase of the frequency of input simple harmonic wave and increases with the increase of strength.Most of the relative displacement between the top and bottom of each timber frame column does not exceed the limit value(1/30),indicating the timber frame has good deformation performance and collapse resistance.(5)The damage of column base increases,the column top acceleration and inter-story displacement angle decrease.The foundation settlement leads to the increase of inter-story displacement angle of the timber frame.Compared with the non-settlement end,the column top acceleration and inter-story displacement angle at the settlement end increase.